Steel Bridges and How They Work
Bridges, the colossal structures that connect humanity. Facilitating trade, cultural and social exchange and more, bridges are essential to mankind thriving. But why do they use steel?
Structural steel has many benefits over other construction materials, in general and especially concerning bridges.
For starters, the biggest and most significant benefit is that it is extremely strong. Smartly using intricate geometrical patterns, the steel bridges remain intact even under immense pressure. It is able to bend without snapping makes it very suitable to handle high tension and compression.
They are Long Lasting Bridges using structural steel have lasted for decades, some even centuries. The golden gate bridge which completed its construction in 1937 is, at the time of writing this blog, 86 years old! With proper maintenance steel will easily outlast any other material.
Using steel is also more efficient and takes less time to construct with. This is because of something called Pre-Fabrication. Where the structures are fabricated off-site, transported, and put together at the building site since barely any reinforcement is required. Think of it like Ikea furniture!
But in contrast to all these benefits, steel hadn’t replaced wrought iron for a while in the construction space. One of the first uses of steel in infrastructure was building bridges. The first Steel Truss bridge started construction in 1867, the Eads bridge in St. Louis which spanned across the Mississippi River.
There is a myriad of steel bridges in the world, each with its own unique structure and purpose; They all follow a certain template or a structural system as they call it. Let me explain the main few of them.
- Let’s start with the Steel Truss Bridge. A steel truss bridge is one containing only trusses. If you’re wondering what a truss is, it’s an assembly of multiple parts put together, to create a triangular rigid structure. These parts now act as more than their own sum, rather as one structure. A Truss bridge takes a bit of time but is overall easier and has a lighter load to carry.
- The second would be the Steel Girder Bridge. A bridge that uses girders to support its deck is called a Girder bridge. A girder is a large beam made of iron or steel, used in building the frameworks of buildings, and in this case in bridges. Girder bridges are easier to maintain due to their simplistic design, they use less materials and hence have a lower impact on the environment and are even cost-effective!
- And finally, the Steel Arch Bridge. Also called a through-arch bridge, it is a type of bridge in which the base arch structure begins and ends under the deck, but the center is above. If that was complicated, a well-known example would be the Sydney Harbour Bridge in Australia. Their functionality rises since they can be flat across long distances but rise above the roads and whatnot when used in the middle of urban settings. Though these are more complex and difficult to build, their strength and durability is unmatched.
Steel Bridges are an essential part of modern infrastructure; they act as the thread sewing our world together, and each one is a societal and constructive marvel.
~ Brhma Trivedi
